August 15, 2008
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Aphid Photos & Information See Start Scouting for Soybean Aphids, July 3 issue of CropWatch |
As of this date the soybean aphid populations have continued to increase and many fields have been sprayed or are waiting to be sprayed. Because the soybeans as a whole are later in maturing, we anticipate aphid activity at least through the end of August. As time goes by it becomes more difficult to justify a spray treatment as aphid populations will begin to decrease as we approach the end of August-early September.
If fields are at threshold levels, treatments will be beneficial through next week. However, the longer it takes to get the field sprayed, the less yield will be protected from loss through aphid feeding.
Having a field one week away from treatment means growers can continue monitoring the field and cancel a treatment if aphid numbers are falling. The soybean aphid experience is a roller coaster. Often populations will hang at low levels, then increase rapidly over a period of 7-10 days. However, once populations begin to drop, they will drop rapidly and 7-10 days later aphids may be hard to find.
Bottom line, those serious about aphid management will have to commit to spending a fair amount of time in the field during the next 7-10 days to monitor aphid activity. Not all fields will need to be sprayed. A lot of spraying is "panic spraying" caused by watching someone else's field get treated. Every field needs to be scouted and evaluated individually.
Keith Jarvi
Extension Integrated Pest Management Assistant
Northeast REC, Norfolk
